Integrated circuit (IC) design, test, reliability, failure analysis and system design teams need the ability to monitor an IC's temperature, in situ. In addition to the average temperature of the IC, transient and/or localized hot spots also need to be detected and addressed by the IC or system. Known methods for measuring such temperature or localized hot spots include the use of one or more thermal resistors, thermal diodes, and/or digital temperature sensors incorporated directly into the IC, preferably in the active area. Other known methods include external sensors such as laser interferometers and solid state thermal imagers to record temperature remotely at each XY grid location or pixel of the IC.
The thermal resistors, thermal diodes, and/or digital temperature sensors, however, use valuable real estate of the IC, within the active areas. Also, the thermal resistors, thermal diodes, and/or digital temperature sensors may not provide accurate readings, because they may be placed far away from any temperature change and as such do not provide the ability to measure the average temperature over a specific predetermined area of the IC. For example, it is not known during the design phase where all of the transient and/or localized hot spots will occur, requiring multiple sensors be spread throughout the most active regions (and most valuable real estate) of the IC. Even then, these sensors may not be located near hot spots created by packaging or other thermal barriers (thermal resistance), or near hot spots created by electrically resistive defects that pass functional, structural, parametric and other testing.
Remote temperature sensors such as laser interferometers and solid state thermal imagers are incapable of accurately measuring the temperature of the IC at subsurface locations when one or more overlying films act to diffuse the heat. These unpredictable hot spots can lead to lower performance (lower revenue), increased test costs, increased system costs, increased operating costs, and premature failure of the IC (lower reliability, lower customer satisfaction, and lower revenue). Other drawbacks of the thermal resistors, thermal diodes, and/or digital temperature sensors include processing dependencies which require calibration in order to obtain measurement accuracies better than 2° C. to 3° C.
Accordingly, there exists a need in the art to overcome the deficiencies and limitations described hereinabove.